Hydraulic accumulator



May 4,1926. 1 1,582,985.

P. T. HNEL HYDRAULIC ACGUMULATOR Filed March 51l 1924 3 Sheets-Sheet l May 4 1926.

P. T'. HNEL HYDRAULIC ACCUMULATOR Patented lli/lay 4, 1926.

-PAUL THEoDoR HNEL, or DRESDEN, GERMANY,

HYDRAULIC ACCUMULATOR.

Application ined March 31, 1924. serial No. 703,302.

To all fwiom t 79mg/ concern.'

Be it known that I, PAUL THEoDon HNEL, a citizen of jGermany, residing at Dresden, Germany, have invented certain new and useful lmprovemei'its in Hydraulic Accumulators, of which the following is a specification.

My invention refers to hydraulic accumulaters, more Yspecially for use in connectionl with hydraulic presses requiring Varying pressure and liquid supply. lt is an object. of my invention to provide means whereby the hydraulic accumulatore are rendered suitable for answering these particular requirements in a more perfect manner than has hitherto been the case.

ils is well known to those skilled in the art', hydraulic presses employed for instance in freeing cocoa from oil, when starting compression, first require a large supply of liquid, the counter-pressure being still low. As compression proceeds, the liquid supply must be gradually reduced while the counterpressure rises slowly at first and near the end of the operation becomes very high.

n order to satisfy these particular requirements with the aid of a hydraulic accumulator, instead of being compelled to vary the pressure to be supplied by it merely by the throttling valve which consumes much energy, 1 provide a plurality of pistons of different useful surface cooperating either with a single cylinder or with a plurality of cylinders which are however in communication with one another, these pistons being subjected to the action of a common load which may be either a weight or compressed air or the like.

' In a hydraulic accumulator' of this kind, having for instance two pistons arranged for reciprocation in one cylinder on liquid being admitted into the cylinder, at first the piston having the larger surface will-do the greater part of the lifting work, While the piston having the smaller surface is carried along and assists the larger piston. During this first stage low pressure prevails in the cylinder. However7 when the larger piston has completed its stroke, being prevented from rising further by a stop, the pressure will rise in the cylinder and the smaller piston will now continue rising and lifting the load. As this load now presses on a far smaller surface, high pressure is created in the cylinder. ln consequence of the correspondingly small surface of the smaller pis ton, only a comparatively small quantity of liquid under pressure can be taken from the cylinder, but, as already mentioned at the beginning, only a smaller quantity of liquid is required at high pressure.

In the drawings affixed to this specification and forming part thereof, three devices embodying my inventionvare illustrated by way of example. In thedrawingsf- Fig. 1 is a. vertical section of an accumulator loaded by a weight and provided with two, and

Fig. 2 a similar view taken on the line H-II in F 3 of an accumulator with three pistons, all arranged for reciprocat-ion in one cylinder.

Fig. 3 is a diagrammatic cross-section disclosing the arrangement .of the pistons in the cylinder of the device shown in Fig. 2.

Figs. 4land 5 are vertical sections, drawn to diierent scales, of an accumulator provided with a. compressed air chamber.

Referring first to Fig. 1 of the drawings, 1 is the cylinder, 2 the large and 3 the small piston. e is the liquid inlet and outlet. 5 is a stuffing box closing the upper end of the cylinder. 6 is the enlarged lower end of the large piston 2 forming a shoulder which prevents the piston from rising in the cylinder beyond the position'shown in the draw ings. 7 is an axial groove in the circumference of the lower end vof piston 2, this groove allowingliquid which may have collected above Vpart .6 to escape into the lower part of the cylinder. 8 is the axial boring of piston 2 serving as cylinder for ythe small piston 3, this boring being closed on top by a stuffing box 9 iXed in place by screw bolts 10. 11 is the hub of a wheelfshaped yoke resting on the upper end of the small piston 3, and 12 is a. flanged ring guided on the circumference of the cylinder 1 and con nected with the yoke by rods 13. 15 is the weight formed of bricks, concrete or the like and reinforced by further rods 14.

In the device illustrated in Figs. 2 and 3, 19 is the cylinder, 2O is the liquid inlet and outlet. 21, 22 and 23 are project-ions of decreasing length extending downwards from the closed top of the cylinder, these projections serving as guides for three pistons 16, 17, 18, respectively, of which 16 has the largest and 18 the smallest useful surface. 24, 24 are stutng boxes serving to pack the upper ends of the piston guides. 25 is the yoke resting on the upper ends of the pistons, 26 is the ring guided on the cylinder, 27 are the rods connecting the ring with the yoke and 28 is the weight carried by them. 29 and 30 are the enlarged lower ends of pistons 16 and 17, respectively, which serve to limit their upward movement. Obviously, this accumulator will act in all respects like the one shown in Fig. 1, with the only exception that on the pair of pistons 17 having completed its upward stroke, the last pair of pistons 18 will continue raising the weight.

In the third modification disclosed in Figs. 4 and 5, 81 is the cylinder, 32 is the liquid inlet and outlet, 38 is the stufling box packing the cylinder, 34 is the larger piston having its stroke limited by a shoulder 35. In the axial boring 36 of this piston is arranged the smaller piston 37 packed by a stuffing box 3S and having a collar 89 adapter to limit the downward stroke. 40 is a head secured to the cylinder 31 by means of flanges 41 on the head and similar flanges 42 on the cylinder connected by rods 43. 44 is an axial boring in the head forming a cylinder in which the upper part of piston 87 is arranged to reciprocate. 45 is a connecting pipe leading from the upper end of boring 44 to a compressed air vessel 46, a threeway cock 47 being inserted between them. 48 is a boring of the valve casing leading` to the outer air.

In this device, if liquid is supplied under pressure to the cylinder 31, the two pistons will be raised and the air will be compressed in 44 and 46, pro-vided that the cock 47 be in the position shown in the drawings. After t-he cock has been closed, liquid is allowed to escape from cylinder 31, but, owing` to the great friction, the small amount of compressed air in the vessel 4G will notl sufiice to press the pistons back into the their initial positions. By establishing a connection between boring 48 of the valve and a compressor (not shown) and turning the cock to establish communication between 48 and 45, while shutting off vessel 46, the pistons are forced back.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person Skilled in the art.

I claim 1. Hydraulic accumulator comprising in combination, a cylinder, means for supplying liquid to said cylinder, two pistons having different useful surfaces arranged in said cylinder for simultaneous reciprocation relative to said cylinder and to each other and a power storing means arranged to be acted upon by said pistons jointly and also by the small piston alone.

2. Hydraulic accumulator comprising in combination, a cylinder, means for supplying liquid to said cylinder, two pistons having different useful surfaces and strokes of different length arranged in said cylinder for reciprocation and a power storing means arranged to be acted upon by said pistons jointly and also by the smaller piston alone.

3. Hydraulic accumulator comprising in combination, a cylinder, means for supplying liquid to said cylinder, two pistons having different useful surfaces arranged in said cylinder for simultaneous reciprocation relative to said cylinder and to each other, the smaller piston being mounted in an axial boring of the larger piston, and a power storing means arranged to be acted upon by said pistons jointly and also by the smaller piston alone.

4. Hydraulic accumulator comprising in combination, a cylinder, means for supplying liquid to said cylinder, a piston arranged for reciprocation substantially in the center' of said cylinder, pistons of smaller useful surface arranged for reciprocation in said cylinder in parallel with said central piston, means for limiting the upward stroke of said pistons, the limiting means connected with said central piston being disposed at a lower level than the limiting means connected with with said smaller piston, and a power storing means arranged to be acted upon by said pistons jointly and also by the smaller piston alone.

5. I-Iydraulic accumulator comprising in combination, a cylinder, means for supplying liquid to said cylinder, two pistons having different useful surfaces arranged in said cylinder for simultaneous reciprocationl relative to said cylinder and to each other and a compressed air vessel arranged to be acted upon by said pistons jointly and also by the smaller piston alone.

In testimony whereof I ai'iix my signature.

PAUL 'rHnoDoR HNEL. 

